I'm using Ubuntu 26.04 LTS on the desktop and have tried several Linux calendar applications, but each seems to have some limitation. KOrganizer, for example, does not appear to let me set a default time zone, possibly because of an issue with the application or its setup package. I'm also interested in an option that can synchronize with other devices, especially since I may use a Linux phone in the future. I'm open to a reasonably priced one-time purchase if it provides a better experience.
4 Answers
Google Calendar can work directly with the desktop if you add the account through Ubuntu’s Online Accounts settings. It’s convenient if you already use Google services, although it does require a Google account.
KOrganizer and the Plasma calendar integration work reasonably well with Google Calendar in my experience. There are a few quirks, but they may be enough for ordinary scheduling.
If the main problem is the time zone, many Linux applications use the TZ environment variable. You could test KOrganizer with a command such as `TZ=Asia/Tokyo korganizer`; that should launch that instance using Tokyo time. For a permanent setting, you could also configure the variable in the application’s desktop launcher or your session environment.
Thunderbird’s calendar is worth considering. It can connect to several Google calendars, and those calendars can continue syncing with your phone independently.
The Arch Wiki maintains a broad list of calendar applications. It is aimed at Arch users, but most of the listed programs should also be available for Ubuntu, so it can be useful for comparing features and checking which ones support synchronization.

I only keep a Google account because I use an Android phone, so I’d prefer something that won’t tie me more closely to that ecosystem.